Protective shield for instrument case

Abstract: An encased electronic instrument of the type having a front panel bearing controls and visual displays that is clamped to the forward periphery of a box-like case, is provided with a resiliently deformable and elastically stretchable identifying shield surrounding and overlying the front panel, and extending a given distance rearwardly generally parallel to the outer surface of the instrument case. The shield is preformed, with an outer peripheral band defining an open center having a shape slightly smaller than, but generally conforming to the outer shape of the front panel and the rearwardly extending outer surfaces immediately adjacent to the front panel. A first inwardly extending flange projects from the forward edges of the peripheral band in overlying relationship with the outer edges of the front panel of the instrument, and a second inwardly extending flange projects from the rearward edges of the peripheral band to enhance frictional engagement between the band and the underlying outer surfaces of the instrument. The second inwardly extending flange may also serve to retain the shield on the front panel and to provide sealing between the panel and the case, by being clamped between the rear surface of the front panel and the forward edges of the side surface portions of the case, replacing the sealing gasket previously described as being used in the prior art. The material from which the shield is formed is resiliently deformable and elastically stretchable, so that it can be stretch-fitted over the front panel of an instrument in peripheral elastically gripping relationship; the thickness of the body of the shield is selected so that the force of unintended impacts with the outer surface of the shield will be absorbed in part in the shield and will be transmitted in part to the abutting surface of a panel in which the instrument is mounted, and will also be transmitted, with reduced intensity, to the outer surface of the instrument. The shield also serves to provide convenient and ready visual differentiation among a plurality of clustered instruments, as in a control board, through the use of distinctive colors which may be applied to the surface of the shield or which may be made an inherent part of the shield material. Visual identification is further enhanced by molding distinctive words or symbols into a visible surface of the shield.

Description: FIELD OF THE INVENTION This invention relates generally to protection against physical damage of instrument cases of the type having controls and visual displays mounted on a front panel, and more specifically relates to a protective shield for the front panels of such instruments as well as to such instruments having protective shields mounted thereon. BACKGROUND OF THE INVENTION Instruments, such as electronic meters, of the type enclosed in a generally rigid housing formed of metal or other suitable material, and having a front panel bearing visual displays and/or control devices in various combinations, are well known. Such instruments have been in general use in commercial, industrial and scientific applications for many years. In the most common configuration, the front panels of such instruments are rectangular in shape, and they are fastened to a rectangular box-like housing having side surface portions extending rearwardly from the four edges of the panel in substantially perpendicular relationship. Frequently, the periphery of the rear surface of the front panel is butted against the forward edges of the side surface portions of the housing, and fasteners such as screws pass through the front panel and engage threaded openings in the housing to clamp the panel and the housing together. Most often, a sealing gasket in the form of a rectangular band is clamped between the rear surface of the front panel and the forward edges of the side surface portions of the housing to seal the corresponding joint against entry of dust, moisture and the like. In a well-known arrangement, a plurality of instruments are mounted in parallel and/or coordinate arrays with the front portion of each instrument projecting slightly forward of a generally planar display "board" that may be positioned vertically or inclined at an angle away from vertical. In other applications, one or more instruments may stand about on table tops or similar support surfaces, close to the sources of the electrical signals that are being controlled and/or displayed. Applications of the type described above frequently involve substantial amounts of physical activity in relatively close proximity to one or more sensitive instruments. Under such circumstances, various objects being handled by operators, such as heavy tools, test specimens, industrial containers and even other electronic and mechanical instruments, frequently and unavoidably come into unintended contact with the exposed front panels of the instruments being used. The shocks, dents and other damage caused by such unintended contacts can result in substantial financial losses, not only through loss of the instruments themselves, but also through such consequences as lost or invalidated test results, incorrect readings of process control measurements and the like. Protecting instruments from such damage is considered a highly desirable goal. In addition, especially in applications involving a plurality of instruments that are similar or identical in appearance, it is highly desirable to provide a means for being able to clearly and conveniently distinguish one instrument from another. The need to distinguish is particularly important where similar or identical instruments are reading or controlling signals that are significantly different from one another. In such circumstances, the consequences of mistaking the readings of one instrument for another can result in serious damage and costs. One proposal for protecting brittle objects such as portable electronic equipment with the use of one form of resilient board has been shown in EPA0508033. Accordingly, this invention seeks to provide a protective shield for the front panel of electronic instruments and the like capable of absorbing shocks and impacts of unintended blows. BRIEF SUMMARY OF THE INVENTION According to a first aspect of the invention, there is provided a protected instrument casing comprising an instrument case of the type having a housing with a front panel and side surface portions extending rearwardly from the edges of said front panel in substantially perpendicular relationship thereto, and a shield comprising: a body portion in the form of a peripheral band of resiliently deformable and elastically stretchable material for surrounding and elastically engaging the side surface portions of an instrument immediately adjacent to its said front panel surface, said band having a forward edge and a rearward edge; a first inwardly extending flange and projecting toward the center of said peripheral band from at least a portion of the forward edge thereof to lie in substantially parallel, overlying relationship with the said front panel of an instrument characterised by; a second inwardly extending flange projecting toward the center of said band from at least a portion of the rearward edge thereof, said second inwardly extending flange having an inner edge for frictionally engaging the adjacent side surface portion of said instrument. According to a second aspect of the invention, there is provided the use of a shield to protect an instrument case of the type having a housing with a front panel and side surface portions extending rearwardly from the edges of said front panel in substantially perpendicular relationship thereto, the shield comprising: a body portion in the form of a peripheral band of resiliently deformable and elastically stretchable material surrounding and elastically engaging the side surface portions of an instrument immediately adjacent to its said front panel surface, said band having a forward edge and a rearward edge; a first inwardly extending flange and projecting toward the center of said peripheral band from at least a portion of the forward edge thereof to lie in substantially parallel, overlying relationship with the said front panel of an instrument; a second inwardly extending flange projecting toward the center of said band from at least a portion of the rearward edge thereof, said second inwardly extending flange having an inner edge frictionally engaging the adjacent side surface of said instrument. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in greater detail, by way of example, with reference to the drawings in which:- Figure 1 is a partially cut-away pictorial representation of an instrument protected by a shield in accordance with this invention. Figure 2 is a front elevation view of a protective shield in accordance with this invention. Figure 3 is a transverse cross-sectional view of the protective shield of Figure 2, taken along line A-A of Figure 2. Figure 4 and 6 are pictorial representations of further embodiments of a protective shield in accordance with this invention. Figure 5 is a partially cut-away pictorial representation of an instrument case protected by an identifying protective shield, not in accordance with this invention. DETAILED DESCRIPTION OF THE INVENTION Referring now more specifically to the drawings, Figure 1 may be seen to illustrate an instrument case (10) having a front panel (12), side panel surface portions (14), and a protective shield (16) surrounding and overlying front panel (12) in peripheral engagement with side surface portions (14). For purposes of illustration only, front panel 12 is shown to include a visual display 18, a slide switch 20 and an indicator light 22. It should be understood readily that these elements of the front panel 12 are intended solely to symbolize respectively the possible display, control and indicator functions of a typical instrument assembly; they are not intended to be regarded as a part of or limitation of any aspect of the invention. The protective shield 16 is formed of any readily available and suitable material that is both resiliently deformable and elastically stretchable. The material preferably should be easily molded by any commonly used manufacturing technique for ease of fabrication, and should be of a thermosetting nature as well, rather than thermoplastic, to resist more effectively, the heat energy and operating temperature characteristics of heat-generating electronic equipment with which it may be expected to be used. If an instrument identification function is desired, the material of shield 16 should be easily colored, preferably by coloring agents that are incorporated as a constituent of the material itself, in a wide variety of different and distinct colors. Color that is incorporated as a constituent of the material so that the color is relatively uniform throughout its body will enhance the identification function and effectiveness of the shield by helping to assure that nicks and other damage or other imperfections on the surface of the shield will not cause distracting loss of color or color variations in localized areas. To enhance the identification function still further, the material of shield 16 should be easily moldable and preferably capable of retaining clear and relatively well-defined shapes in the manner of bas-relief sculpture, so that letters, numbers, symbols and other identifying indicia may be formed and clearly discerned on the surface of a formed shield, as shown for example, by the letters "T-E-S-T" at 30, in Figure 5. Referring again to the drawings, and specifically to Figure 3, shield 16 may be seen to comprise generally a peripheral band 24 formed of the selected material, surrounding a central opening 26 which is configured to expose the front panel 12 of an instrument case 10 for ready access and viewing, as shown in Figure 1. A first inwardly extending flange 28 projects inwardly toward opening 26 from a forward edge of band 24. A second inwardly extending flange 32 projects similarly toward opening 26 from a rearward edge of band 24 in spaced relation to the first flange 28. The thickness of flange 28 as well as the thickness of band 24 should be chosen in light of the resilience parameters of the material of the shield, to provide a desired degree of resilient cushioning protection for the underlying instrument case. Further, it should be recognized that the thickness of flange 28 defines a recess which positions the front panel 12 of an inserted instrument case 10 a given distance behind the forwardmost surface of the shield 16; the given distance is equal to the thickness of the flange 28, and this thickness therefore should be selected to provide whatever recess effect may be desired in a particular application. Figure 1 illustrates, in particular, the effect on rearward flange 32, of the peripheral elastic engagement of band 24 with the outer side surfaces 14 of an instrument case 10. Specifically, as the band 24 urges the base of flange 32 into engagement with a side surface 14, the deformable qualities of the shield material permits compression of the length of flange 32, while at the same time allowing band 24 to be bowed away from the surfaces 14 in response to the compression forces on flange 32. The result of this combined compression and bowing is a small space 34 adjacent to the inner surface of flange 32, as shown in Figure 1. It has been found that the creation of this small space and the corresponding engagement of the lower inner edge 33 of flange 32 with side surface 14 of case 10 enhances the overall retention of shield 16 on case 10. In Figures 1, 2 and 3 of the drawings, the flanges 28 and 32 are shown to extend in continuous peripheral relation around all sides of the opening 26; it should be understood, however, that either flange may be interrupted, if desired, and portions my be eliminated in whole or in part to accommodate special configurations of an instrument case, or to meet other specific requirements of particular applications, while remaining entirely within the meaning and intent of this invention. For example, in Figure 4, another embodiment of this invention comprises a shield 16', in which a lower forward portion of the first flange 28' has been removed to expose a forward edge 27' of peripheral band 24'. The forward edge 27' may be made as shown to lie substantially flush with the plane of the front panel 12 of an inserted instrument case 10, or it may be made to extend forwardly relative to the illustrated position so that it is more nearly flush with the frontmost surface of flange 28', to provide additional protection for the front panel 12 of an instrument case 10 without overlying or in any way obstructing the lower edge of the front panel. Figure 5 illustrates a shield 16'' carried on an instrument case 10'' comprises a peripheral band 24'' and a first forwardly positioned flange 28'' only, without a rearward flange according to the present invention. Elimination of the rearward flange facilitates assembly of the shield and the instrument case under some circumstances although it is recognized that some of the enhanced retention force advantages of the rear flange may be lost, as a result. The forward flange 28'' surrounds and overlies the front panel 12" of the instrument case 10" in the manner previously described, while the shield is retained on the instrument case 10" solely by the peripheral elastic grip of band 24". Figure 5 further illustrates an example of a protective shield with raised identifying indicia 30, here shown in the form of the letters "T-E-S-T". As explained previously herein, the indicia 30 may be molded into the body of the shield 16" during the fabrication process, and serve the purpose of allowing the shield and the instrument case with which it is associated to be identified easily and conveniently, independently of or in addition to the color of the shield. In the further embodiment of a shield in accordance with this invention illustrated in Figure 6, the forward inwardly extending flange (228) of a shield (216) extends as previously described, from a peripheral band (224) and includes an enlarged lower portion which is provided with one or more through openings (252). These are provided specifically to permit access to underlying parts of a front panel on which it is mounted; accordingly, the lower portion of the flange (228) is dimensioned to overly a greater portion of the front panel (112) than does, say, the upper portion of the same flange. It will be readily understood, as illustrated clearly in the drawing, that opening or openings (252) may supplement or entirely replace the central opening (226) without altering the function or operation of forward flange (228) in accordance with the disclosure of this invention. In general terms, it will be appreciated that the above described invention provides a protective shield and protected instrument case. An encased electronic instrument of the type having a front panel bearing controls and visual displays that is clamped to the forward periphery of a box-like case, is provided with a resiliently deformable and elastically stretchable identifying shield surrounding and overlying the front panel, and extending a given distance rearwardly generally parallel to the outer surface of the instrument case. The shield is preformed, with an outer peripheral band defining an open centre having a shape slightly smaller than, but generally conforming to the outer shape of the front panel and the rearwardly extending outer surfaces immediately adjacent to the front panel. A first inwardly extending flange projects from the forward edges of the peripheral band in overlying relationship with the outer edges of the front panel of the instrument, and a second inwardly extending flange projects from the rearward edges of the peripheral band to enhance frictional engagement between the band and the underlying outer surfaces of the instrument. The second inwardly extending flange may also serve to retain the shield on the front panel and to provide sealing between the panel and the case, by being clamped between the rear surface of the front panel and the forward edges of the side surface portions of the case, replacing the sealing gasket previously described as being used in the prior art. The material from which the shield is formed is resiliently deformable and elastically stretchable, so that it can be stretch-fitted over the front panel of an instrument in peripheral elastically gripping relationship; the thickness of the body of the shield is selected so that the force of unintended impacts with the outer surface of the shield will be absorbed in part in the shield and will be transmitted in part to the abutting surface of a panel in which the instrument is mounted, and will also be transmitted, with reduced intensity, to the outer surface of the instrument. The shield also serves to provide convenient and ready visual differentiation among a plurality of clustered instruments, as in a control board, through the use of distinctive colours which may be applied to the surface of the shield or which may be made an inherent part of the shield material. Visual identification is further enhanced by moulding distinctive words or symbols into a visible surface of the shield.

Claims: A protected instrument casing comprising an instrument case (10) of the type having a housing with a front panel (12) and side surface portions (14) extending rearwardly from the edges of said front panel (12) in substantially perpendicular relationship thereto, and a shield (16,216) comprising: a body portion in the form of a peripheral band (24,224) of resiliently deformable and elastically stretchable material for surrounding and elastically engaging the side surface portions (14) of an instrument immediately adjacent to its said front panel surface (12), said band (24,224) having a forward edge and a rearward edge; a first inwardly extending flange (28,228) and projecting toward the center of said peripheral band (24,224) from at least a portion of the forward edge thereof to lie in substantially parallel, overlying relationship with the said front panel (12) of an instrument; characterised by; a second inwardly extending flange (32) projecting toward the center of said band (24,224) from at least a portion of the rearward edge thereof, said second inwardly extending flange (32) having an inner edge for frictionally engaging the adjacent side surface portion of said instrument. A protected instrument casing in accordance with Claim 1 wherein: a small vacant space (34) exists adjacent to the inner surface of said second inwardly extending flange (32), between the side surface portion of said case (10) and the opposed inner surface of said peripheral band (24,224), due to compression of said second inwardly extending flange (32) against the side surface portions of said instrument case (10) under the elastic forces of said peripheral band (24,224). A protected instrument casing in accordance with Claim 1 or 2, wherein: said shield (16,216) is preformed in a substantially four-sided rectangular configuration having a generally open center, and said first inwardly extending flange (28,228) projects from the forward edge of each one of the four sides thereof in substantially continuous array. A protected instrument casing in accordance with Claim 3, wherein: said second inwardly extending flange (32) projects from the rearward edge of each one of the four sides of said shield (16,216) in substantially continuous array. A protected instrument casing in accordance with any preceding Claim, wherein: the thickness of said first inwardly extending flange (28,228) defines a recess which locates the front panel surface of an inserted instrument in a recessed position rearwardly relative to the forward most outer surface of the said first inwardly extending flange (28,228). The use of a shield to protect an instrument case (10) of the type having a housing with a front panel (12) and side surface portions (14) extending rearwardly from the edges of said front panel (12) in substantially perpendicular relationship thereto, the shield (16,216) comprising: a body portion in the form of a peripheral band (24,224) of resiliently deformable and elastically stretchable material surrounding and elastically engaging the side surface portions (14) of an instrument immediately adjacent to its said front panel surface (12), said band (24,224) having a forward edge and a rearward edge; a first inwardly extending flange (28,228) and projecting toward the center of said peripheral band (24,224) from at least a portion of the forward edge thereof to lie in substantially parallel, overlying relationship with the said front panel (12) of an instrument; a second inwardly extending flange (32) projecting toward the center of said band (24,224) from at least a portion of the rearward edge thereof, said second inwardly extending flange (32) having an inner edge frictionally engaging the adjacent side surface portion of said instrument. The use in accordance with Claim 6, wherein: a small vacant space (34) exists adjacent to the inner surface of said second inwardly extending flange (32), between the side surface portion of said case (10) and the opposed inner surface of said peripheral band (24,224), due to compression of said second inwardly extending flange (32) against the side surface portions of said instrument case (10) under the elastic forces of said peripheral band (24,224). The use in accordance with Claim 6 or 7, wherein: said shield (16,216) is preformed in a substantially four-sided rectangular configuration having a generally open center, and said first inwardly extending flange (28,228) projects from the forward edge of each one of the four sides thereof in substantially continuous array. The use in accordance with any one of Claims 6 to 8, wherein: the thickness of said first inwardly extending flange (28,228) defines a recess which locates the front panel surface of an inserted instrument in a recessed position rearwardly relative to the forwardmost outer surface of the said first inwardly extending flange (28,228).

Inventors: ANGRAVE JANICE E, HOLLANDER MILTON BERNARD, JACOBS DAVID R, ANGRAVE, JANICE E., HOLLANDER, MILTON BERNARD, JACOBS, DAVID R.
Applicants: OMEGA ENGINEERING, OMEGA ENGINEERING, INC.
Application year: 1994
Main classification: G12B9
IPC codes: G12B9